Title: Acoustics of a counter-rotating shrouded propfan - Prediction and data
Abstract: The acoustic characteristics of a counter-rotating integrated shrouded propfan are studied both theoretically and experimentally. The calculation method comprises the main noise generation mechanisms of the propulsor as steady rotor blade loading noise, rotor/rotor and rotor/struts interaction noise, inlet flow distortion noise, and broadband noise. It accounts for flow, duct, and blade sweep effects, sound reflection from the blade rows, and propagation through inlet and nozzle. The calculation model is verified by measurements taken with a 0.4m-diam, air turbine driven propfan model with 10 blades on each of the two rotors in the German-Dutch Wind Tunnel DNW. Deviations between calculated and measured results are attributed to mode and frequency conversion effects occurring when the sound from the rear rotor is reflected from the front rotor and when it is transmitted through the struts. A parametric study showed that the frequency and directivity characteristics of the sound field of a fan with slightly different blade numbers on both rotors are similar to those of a fan with equal rotor blade numbers. Both blade sweep and tip speed have a small influence on far-field noise, but a considerable influence on cabin noise, according to the calculation. Takeoff far-field noise can be reduced by increasing the axial distance between the rotors.
Publication Year: 1995
Publication Date: 1995-09-01
Language: en
Type: article
Indexed In: ['crossref']
Access and Citation
Cited By Count: 4
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